286 Character Animation with Direct3D //Calculating the binormal and setting //the tangent binormal and normal matrix float3x3 TBNMatrix = float3x3(tangent, binormal, normal); //Setting the lightVector OUT.lightVec = mul(TBNMatrix, lightDir); OUT.lightHalf = mul(TBNMatrix, vHalf); OUT.tex0 = IN.tex0; return OUT; } //Pixel Shader float4 morphNormalMapPS(VS_OUTPUT IN) : COLOR0 { //Calculate the color and the normal float4 color = tex2D(DiffuseSampler, IN.tex0); //This is how you uncompress a normal map float3 normal = 2.0f * tex2D(NormalSampler, IN.tex0).rgb - 1.0f; //Get specular float4 specularColor = tex2D(SpecularSampler, IN.tex0); //Set the output color float diffuse = max(saturate( dot(normal, normalize(IN.lightVec))), 0.2f); float specular = max(saturate( dot(normal, normalize(IN.lightHalf))), 0.0f); specular = pow(specular, 85.0f) * 0.4f; return color * diffuse + specularColor * specular; } Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. Chapter 12 Wrinkle Maps 287 Figure 12.13 shows another screenshot of the Soldier’s face using somewhat “exaggerated” highlights. Note that this isn’t the kind of result you’d actually want for skin. The examples and images in this chapter are a bit exaggerated to emphasize the effect of the specular highlights. EXAMPLE 12.2 Example 12.2 contains all the code for implementing specular highlights. Play around with the shininess value in the pixel shader, and if you have good image-editing software, play around with the specular map as well. This example also implements specular highlights for the old diffuse lighting model (used for the eyes in the example, which are not normal mapped). Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 288 Character Animation with Direct3D WRINKLE MAPS You’ve now arrived at the goal of this chapter: the wrinkle maps. These maps are basically an animated or weighted normal map that is connected to the move- ment of the face. For example, smiling may reveal the dimples in the cheeks of the characters. These small deformations occur as a result of the underlying muscles in the face moving. Another example of this phenomenon is wrinkles that appear (or disappear) on the forehead as a person raises or lowers his or her eyebrows. FIGURE 12.13 Exaggerated highlights. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. Chapter 12 Wrinkle Maps 289 The use of wrinkle maps in games is still a recent addition, and most games today don’t bother with it unless the characters are shown in close-up. Figure 12.14 shows a grayscale image of a normal map containing wrinkles for the forehead and dimples. Note that the wrinkles in Figure 12.14 have been made somewhat extreme to stand out a bit better (for educational purposes). Normally, wrinkle maps are something you don’t want sticking out like a sore thumb. Rather, they should be a background effect that doesn’t steal too much of the focus. Next, you need to encode which regions of the wrinkle map should be affected by which facial movements. In the upcoming wrinkle map example, I’ve used a separate texture to store masking of the wrinkle map regions. You could, however, also store this data in the vertex color, for example. Figure 12.15 shows the mask used to define the three different regions of the wrinkle map. FIGURE 12.14 Wrinkle normal map. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 290 Character Animation with Direct3D In Figure 12.15, three different regions are defined. The Red channel defines the part of the face that isn’t affected by animated wrinkles. The Green channel defines the forehead wrinkles, and the Blue channel defines the two dimple areas at either side of the mouth. To the shader we will upload two blend values (depending on what emotion or shape the character’s face has). These two values are called fore- headWeight and cheekWeight. At each pixel, we sample the blend map, multiply the Green channel with the foreheadWeight and the Blue channel with the cheekWeight. The resulting value is used to fade the normal in/out from the wrinkle normal map. The following code snippet shows how this is done in the pixel shader: //Pixel Shader float4 morphNormalMapPS(VS_OUTPUT IN) : COLOR0 { //Sample color float4 color = tex2D(DiffuseSampler, IN.tex0); //Sample blend from wrinkle mask texture float4 blend = tex2D(BlendSampler, IN.tex0); //Sample normal and decompress float3 normal = 2.0f * tex2D(NormalSampler, IN.tex0).rgb - 1.0f; //Calculate final normal weight float w = blend.r + foreheadWeight * blend.g + cheekWeight * blend.b; FIGURE 12.15 Wrinkle map mask. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. Chapter 12 Wrinkle Maps 291 w = min( w, 1.0f ); normal.x *= w; normal.y *= w; //Re-normalize normal = normalize( normal ); //Normalize the light float3 light = normalize(IN.lightVec); //Set the output color float diffuse = max(saturate(dot(normal, light)), 0.2f); return color * diffuse; } EXAMPLE 12.3 Example 12.3 has the full implementation for the wrinkle maps. You can find how the weights for the forehead and dimples are set in the render method of the Face class. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 292 Character Animation with Direct3D Figure 12.16 shows the wrinkle maps in action. Thanks to Henrik Enqvist at Remedy Entertainment for the idea of covering wrinkle maps. He also graciously supplied the example code for the wrinkle map example. CONCLUSIONS This chapter covered all aspects of normal mapping, from the theory of normal maps to how to create them and how to apply them on a real-time character. This base knowledge then allows you to implement the more advanced wrinkle maps as an animated extension to normal maps. I hope you managed to understand all the steps of this somewhat complex process so that you’ll be able to use it in your own projects. The DirectX SDK also has skinned characters with high-quality normal maps, which are excellent to play around with. I also touched briefly on implementing a specular lighting model—something that, together with normal maps, really makes your character “shine.” After the slight sidetrack this chapter has taken, I’ll return to more mainstream character animation again. Next up is how to create crowd simulations. CHAPTER 12 EXERCISES Implement normal mapping for the SkinnedMesh class using the code in the Face class as a base. FIGURE 12.16 Wrinkle maps in action. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. Chapter 12 Wrinkle Maps 293 Implement normal mapping without supplying the binormal from the mesh, but calculate it on-the-fly in the vertex shader. Implement support for multiple lights (for both normal mapping and specular highlights). FURTHER READING [Cloward] Cloward, Ben, “Creating and Using Normal Maps.” Available online at http://www.bencloward.com/tutorials_normal_maps1.shtml. [Gath06] Gath, Jakob, “Derivation of the Tangent Space Matrix.” Available online at http://www.blacksmith-studios.dk/projects/downloads/tangent_ matrix_derivation.php, 2006. [Green07] Green, Chris, “Efficient Self-Shadowed Radiosity Normal Mapping.” Available online at http://www.valvesoftware.com/publications/2007/SIGGRAPH 2007_EfficientSelfShadowedRadiosityNormalMapping.pdf, 2007. [Hess02] Hess, Josh, “Object Space Normal Mapping with Skeletal Animation Tutorial.” Available online at: http://www.3dkingdoms.com/tutorial.htm, 2002. [Lengyel01] Lengyel, Eric. “Computing Tangent Space Basis Vectors for an Arbitrary Mesh.” Terathon Software 3D Graphics Library. Available online at http://www.terathon.com/code/tangent.html, 2001. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. This page intentionally left blank Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 295 Crowd Simulation13 This chapter introduces the concept of crowd simulation and how it can be used in games to control large groups of NPCs. You will first get familiar with the ancestor of crowd simulation—namely, flocking behaviors. With flocking behaviors it is possible to control a large group of entities, giving them a seemingly complex group behavior using only a few simple rules. This idea is then carried over to crowd simulation and extended to create some even more complex behaviors. Here’s what will be covered in this chapter: Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. [...]... weighing the different steering behaviors For example, it might be more important that they avoid colliding with each other (Separation) than it is that they stay together as a group (Cohesion) ease purchase PDF Split-Merge on www.verypdf.com to remove this watermark 304 Character Animation with Direct3D I NTRODUCTION TO C ROWD S IMULATION There’s a lot of academic research being done in the crowd... forces are calculated and used to update the velocity and position of the Boid To manage a flock of Boids, I’ve created the Flock class like this: ease purchase PDF Split-Merge on www.verypdf.com to remove this watermark 300 Character Animation with Direct3D class Flock { public: Flock(int numBoids); ~Flock(); void Update(float deltaTime); void Render(bool shadow); void GetNeighbors(Boid* pBoid, float... im_position m_position; float distToNeightbor = D3DXVec3Length(&vToNeighbor); ease purchase PDF Split-Merge on www.verypdf.com to remove this watermark 302 Character Animation with Direct3D if(distToNeightbor < SEPARATION_LIMIT) { //Too close to neighbor float force = 1.0f - (distToNeightbor / SEPARATION_LIMIT); separationForce -= vToNeighbor... is called Alignment, and it states that a Boid should steer toward the average heading of its local neighbors This rule is shown in Figure 13.2 ease purchase PDF Split-Merge on www.verypdf.com to remove this watermark 298 Character Animation with Direct3D FIGURE 13.2 Alignment Cohesion The third and last rule of the Boid steering behaviors is called Cohesion It keeps the flock together by making a...296 Character Animation with Direct3D Flocking behaviors “Boids” implementation Basic crowd simulation Crowd simulation and obstacle avoidance F LOCKING B EHAVIORS Let’s start from the beginning Like many other algorithms... Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark Chapter 13 Crowd Simulation 303 //Cap Y position m_position.y = max(m_position.y, 1.0f); } In addition to the three normal Boid steering behaviors, I have added a steertoward-point force (for keeping the Boids in the camera’s view frustum) and an avoid-the-floor force, for making sure the Boids don’t crash with the floor Other... technique has been successfully applied to packet routing in networks Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark Chapter 13 Crowd Simulation 297 BOIDS In 1986, Craig Reynolds made a computer simulation of three simple steering behaviors for a group of creatures he called “Boids.” With only three simple steering rules he managed to show some surprisingly complex emergent... purchase PDF Split-Merge on www.verypdf.com to remove this watermark Chapter 13 Crowd Simulation 305 class CrowdEntity { friend class Crowd; public: CrowdEntity(Crowd *pCrowd); ~CrowdEntity(); void Update(float deltaTime); void Render(); D3DXVECTOR3 GetRandomLocation(); private: static SkinnedMesh* sm_pSoldierMesh; Crowd* m_pCrowd; D3DXVECTOR3 m_position; D3DXVECTOR3 m_velocity; D3DXVECTOR3 m_goal; ID3DXAnimationController*... even more likely that a third ant will follow the first two Once the food source has been depleted, the ants will stop laying the trail and the pheromones will evaporate with time, stopping ants from wasting time down that trail So with these seemingly simple rules that each individual follows, the community as a whole still runs a pretty complex operation This specific example has even spawned its... nearest neighbors would be to use a space partitioning tree, such as a KD-tree See the following URL for a good introduction to KD-trees: http://en.wikipedia.org/wiki/Kd-tree Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark Chapter 13 Crowd Simulation 301 Since each Boid object contains a pointer to its flock, it can use the GetNeighbors() function to find any neighboring Boids . colliding with each other (Separation) than it is that they stay together as a group (Cohesion). Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 304 Character Animation with. map. FIGURE 12.14 Wrinkle normal map. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 290 Character Animation with Direct3D In Figure 12.15, three different regions. the render method of the Face class. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. 292 Character Animation with Direct3D Figure 12.16 shows the wrinkle maps in